It is well established that many organophosphorus compounds are powerful neurotoxic agents that inhibit acetylcholinesterase (AchE) by the process of phosphorylation. A particularly dangerous class of organophosphorous compounds is the phosphoryl fluoride containing species. Two such species are the chemical warfare agents (CWA) sarin (isopropyl methylphosphonofluoridate) and soman (pinacolyl methylphosphonofluoridate), referred to as GB and GD agents, respectively. For obvious safety reasons, CWA may be modeled using a chemical warfare agent simulant. Common CWS are diisopropyl fluorophosphate (DFP) and diethyl chlorophosphate (DCP).
There has been a significant interest in the decontamination and detection of CWA over the last five decades, with a large focus on phosphorylfluoride nerve agents e.g., Sarin and Soman. Chemical detection of CWA has been a long-term ambition for many researchers, even more so in this day and age due to the continuing global threat of terrorist activity. One approach that has been studied uses chromogenic detector reagents, which directly bind to a target nerve agent causing a modulation in the emitted UV-Vis wavelength. However, there are limitations in the colorimetric systems developed thus far, including low sensitivity and slow response times.
One current method for detecting CWA produces a dramatic spectral change created in response to the cyclization of a flexible chromophore. See S. W. Zhang & T. Swager, J. Am. Chem. Soc. 125, 3420 (2005). The system creates a rigid and highly conjugated fluorophore on the addition of DFP, causing an “off-on” response in the micromolar concentration range. However, the system utilizes an alcohol as a nucleophile, and hence the rate of reaction with DFP, let alone that anticipated with sarin/soman, is quite slow (half-life approaching an hour).
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While the present disclosure is susceptible to various modifications and alternative forms, specific example embodiments have been shown in the figures and are herein described in more detail. It should be understood, however, that the description of specific example embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, this disclosure is to cover all modifications and equivalents as defined by the appended claims.